Once this has been defined somewhere you can use the default OpenGL commands to create a shader, I chose to use the demo code / shader here the main thing to remember is that you must use GL_PATCHES to draw to the tessellation units.

The other problem is that code like

glPatchParameteri(GL_PATCH_VERTICES, 16);

is not available as the glPatchParam functions are not exposed, the good news is that you can set all of this in the shader so it is not too much of an issue. The updates have now been rolled into the core ngl library, and I will add some demos soon.

Next you need to follow the instructions here to install and setup NGL, you will need to install bzr which is a simple package from here.
Finally this example shows how to build the Qt 5 version of NGL and a basic demo